Team assignment within design and construction largely occurs following notice of selection to the winning firm. Upon notification, most firms use informal methods based primarily on qualifications and availability as the key factors in team assignment. Past experience with the client, current geographic location, and other variables may also be considered. Regardless of the specific considerations, team assignment mechanics within the built environment lack a sophistication consistent with the known importance of the project team to achieving successful project outcomes. One of the most overlooked components of team assignment mechanics is the significance of the "personality traits" in building teams and ensuring the various members have a high probability of being able to work and communicate effectively with each other. This paper studied the effect of honesty/humility and extraversion (from HEXACO PI-R test), and overall emotional intelligence (from emotional intelligence test, version 2.0) on team performance. A case study of 102 AEC industry professionals working in teams to complete similar project management tasks is presented. In the case study, teams specifically aligned considering these personality traits are compared to teams of random formation. Teams that were formed considering personality traits outperformed teams that were randomly formed by 68%. The findings of this study can be used to strategically form high performing teams.